Mayor Bill de Blasio’s child welfare commissioner turned her back on a safety program that was a key reform adopted in the wake of the infamous 2006 beating death of little Nixzmary Brown, The Post has learned.

The Administration for Children’s Services modeled its “ChildStat” program after the NYPD’s widely copied CompStat crime-fighting initiative, holding weekly meetings at which abuse cases are randomly reviewed for shortcomings.

But ACS Commissioner Gladys Carrión — who abruptly quit amid furor over a series of child deaths tied to her agency — all but stopped attending ChildStat sessions shortly after taking office in 2014, three former city officials said.

As a result, ACS caseworkers now rarely show up for the meetings at which their investigations are analyzed, said the sources, who include a recently retired ACS supervisor.

Under terms of their contract, caseworkers — who directly investigate allegations of abuse — cannot be forced to attend, but they were “strongly encouraged” during the previous administration of former Mayor Michael Bloomberg, sources said.

“They were asked questions like, ‘Why didn’t you do this? Why not do that? How far back did you go into the past to investigate?’ ” the ex-supervisor said.

“A lot of workers were concerned about being written up for failing to follow protocol, or worse, if they didn’t answer questions the right way.”

ChildStat proved so effective that it has been adopted by child welfare agencies in New Jersey and Philadelphia, according to a 2015 report by the Annie E. Casey Foundation.

Carrión also changed the focus of ChildStat from nuts-and-bolts practices to larger policy issues, the sources said, and pulled the plug on closed-circuit broadcasts intended to let staffers around the city watch and learn from the sessions.

Carrión submitted her resignation in December, just one day before the state released a scathing report that faulted ACS for repeatedly botching probes into the abuse of 7-year-old Zymere Perkins, who was beaten to death in a squalid East Harlem apartment on Sept. 26.

ACS has also come under fire for its handling of two other fatally beaten children: Jaden Jordan, 3, of Brooklyn and Mikey Guzman, 5, of Queens.

De Blasio has yet to name a replacement for Carrión, whose last day on the job was Feb. 3.

ACS spokeswoman Aja Worthy-Davis insisted Carrión only “rarely” missed any ChildStat meetings, but declined to provide minutes or other records to document her attendance.

Worthy-Davis said officials “do not believe the culture was changed” and said the video feed was canceled because it was “ineffective.”

“The focus of the ChildStat meetings was always, and is currently, on senior management,” she said.